I have a house built in the 1940s. Just last year, we had the main sewer line to the street replaced so I know my issues aren't from a general sewage line.

The people that lived in the house before us did a bit of work in the basement including installing a shower. BUT...the shower often backs up with water. This is really the first time it's backed up since we had the sewer line replaced. I'm not sure if they are related but it makes me wonder.

Anyway, I've tried to plunge and got some soot out. Then I tried to snake. I have an electrical snake and am not getting anywhere with that. I've put in a whole bottle of drano and nothing has worked. It's gotten to the point that the water just stands and drains only slowly overnight and such.

More clues...I also have an outside drain at the foot of the steps leading into the basement from the outside that sediment has accumulated in and is a slow drain.

I don't think the contractor would have lead the shower drain to that pipe but the timing of the two clogs makes me wonder.

All the other drains in the basement work fine. I have a toilet and a sink in a different bathroom on the other side of the drain.

I have not checked out the vent on the roof. This drain has always been a consistent issue but it's been tolerable until now. Any advice would be appreciated.